The phosphor layers used in X-ray image converter devices are generally deposited from a liquid suspension at carefully controlled thicknesses to govern the quality of the light images produced therefrom. A conventional method to deposit such phosphor layers in an X-ray screen construction employs a doctor blade producing a physical alignment of the plate-like rare earth oxyhalide phosphor particles generally parallel to the longitudinal axis of said phosphor layer. Typical 8 micron average median diameter size lanthanum oxybromide particles (APD), as measured by conventional Coulter Counter instrument, have dimensions of about 3.times.12.times.12 microns. In the normal doctor blade operation, the aforementioned flat and parallel alignment of these phosphor particles is atttributable to a velocity gradient produced by said doctor blade during streamline flow of the liquid phosphor suspension while being deposited. Since the phosphor particle thickness in the direction of an associated photographic film is thereupon only about 3 microns, any light photon generated in said phosphor layer can have as many as 50 scattering events before reaching the associated photographic film in a typical 150 micron thick phosphor layer screen device. Such light scattering produces loss of sharpness in the recorded light image which is understandably not desirable. Moreover, because the phosphor particle size in said phosphor layer, is about 12 microns in the opposite direction along the longitudinal axis of said phosphor layer, there occurs a spreading of the light image resulting in still further loss of clarity for the recorded image. Reduction of these problems in X-ray image converter devices utilizing these phosphor materials would not only improve image sharpness and speed but further reduce quantum noise in the recorded image by increased utilization of emitted light from the phosphor layer.
It would be desirable, therefore, to improve the physical alignment of these phosphor particles in the phosphor layer of an X-ray image converter device and to do so in a manner not requiring elaborate modification of the method now being used to produce these phosphor layers. It would be further desirable to provide such improvement in a manner which affords still other performance advantages to said modified phosphor layers.